Recently, operators have found it useful to use robotic devices to assist in the performance of surgical procedures. A robotic device typically includes a moveable arm having a free, distal end, which may be placed with a high degree of accuracy. A tool that is applied to the surgical site attaches to the free end of the arm. The operator is able to move the arm and thereby precisely position the tool at the surgical site to perform the procedure.
In robotic surgery, virtual boundaries are created prior to surgery using computer aided design software to delineate areas in which the tool may maneuver from areas in which the tool is restricted. For instance, in orthopedic surgery a virtual cutting boundary may be created to delineate sections of bone to be removed by the tool during the surgery from sections of bone that are to remain after the surgery.
A navigation system tracks movement of the tool to determine a position and/or orientation of the tool relative to the virtual boundary′. The robotic system cooperates with the navigation system to guide movement of the tool so that the tool does not move beyond the virtual boundary. Virtual boundaries are often created in a model of a patient's bone and fixed with respect to the bone so that when the model is loaded into the navigation system, the navigation system may track movement of the virtual boundary by tracking movement of the bone.
Operators often desire dynamic control of the tool in different cutting modes during a surgical operation. For example, in some instances, the operator may desire a manual mode to control the tool manually for bulk cutting of the anatomy. In other instances, the operator may desire to control the tool in an autonomous mode for automated and highly accurate cutting of the anatomy. In conventional systems, a virtual boundary associated with a target surface of the anatomy remains active regardless of the mode of control. In other words, the same virtual boundary is on whether the tool is controlled in the autonomous mode or manual mode, for example. The manipulator generally does not allow advancement of the tool beyond the boundary in either mode. However, in some cases, the manipulator may inadvertently allow movement of the tool beyond the boundary. For instance, in the manual mode, the operator may apply such a large amount of force on the tool that exceeds the ability of the manipulator to prevent movement of the tool beyond the boundary. In this case, cutting of the anatomy may occur beyond the virtual boundary thereby deviating from the desired target surface.
There is a need in the art for systems and methods for solving at least the aforementioned problems.